Scientists Work To Understand How Color Vision Is Processed

March 25, 2008

New York University biologists have mapped the medulla circuitry in fruit flies, setting the stage for subsequent research on how color vision is processed. The work, which appeared in the journal Current Biology, will allow future scholarship to explore how color vision is processed in the optic lobe of the fruit fly Drosophila, providing a paradigm for more complex systems in vertebrates.

The research was conducted by postdoctoral fellow Javier Morante and Professor Claude Desplan of NYU’s Center for Developmental Genetics. The study was supported by a grant from the National Institutes of Health.

Eyes have been optimized to process maximum amounts of information by perceiving different parameters of the visual world and responding to them. The eyes can perform several major functions, from simple detection of light for clock synchronization to formation of images. The image of the environment formed by the optics of the eye on the retina is then transferred to brain processing centers. Both retina and brain processing centers have specialized morphology and function to achieve their various tasks.

In this study, the researchers studied processing of color vision, which requires comparison between photoreceptors that are sensitive to different wavelengths of light. They examined the fruit fly Drosophila. Genetic tools in fruit flies are extremely powerful and therefore allow for in depth analysis of neural circuits. In Drosophila, color vision is achieved by specialized photoreceptors that contain different rhodopsins, the photopigments that detect specific wavelengths of light and compare their output in the optic lobes.

Morante and Desplan reconstructed the neural network in Drosophila’s medulla–the brain structure where color photoreceptors project–focusing on neurons likely to be involved in processing color vision. In this endeavor, they identified the full complement of neurons in the medulla. They also developed highly specific analytical tools that will allow scientists to functionally manipulate the network and test both activity and behavior.

“Future experiments using our results will help reveal the exact function of the optic lobe cells in these complex circuits and to reach a better understanding of the mechanisms that govern the physiology of vision both in invertebrates and vertebrates,” said Desplan.